1. Field of the Invention
The present invention relates to a laser scanning system and, more particularly, to a method for operating a 3-D autoscanning LIDAR system.
2. Description of the Related Art
It is often desirable to have computer models of large physical structures, such as a petroleum refinery. Computer models facilitate an understanding of the structure that is beneficial in a number of ways. One technique for constructing these computer models is to use a laser scanning system such as the system described in U.S. patent application Ser. No. 09/177,913. (The ""913 application is a continuation of Ser. No. 08/638,961 which, in turn, is a continuation of International Application No. PCT/US97/06793. Application ""06793 has International Publication No. WO 97/40342.)
The ""913 system includes a combination laser scanner and PC software system that measures, visualizes and models large structures and sites with high speed, high accuracy and over a large range. In use, the device is oriented towards the scene and the user selects the desired measurement area and measurement point spacing. A detailed 3-D geometry of exposed surfaces is remotely captured in the form of a dense, accurate, three dimensional point cloud.
The ""913 system includes a passively Q-switched pulsed laser. The laser beam is scanned over the target using computer-controlled galvo scanning mirrors. The system includes a video monitor for capturing the scene and displaying it on a computer such as a laptop. Using this video image, the operator can select the area to be scanned by the laser.
The galvo mirrors direct the laser through repeated vertical scans, moving over horizontally after each vertical scan. By accurately monitoring the time of flight of each laser pulse out from the device and back into the device, exact positional information of the target can be calculated.
Each measured point has associated with its 3-D information in the point cloud. The system software can display the point cloud to the user. As discussed herein in greater detail, the point cloud can be used to directly carry out a number of procedures. In addition, the system can process the point clouds into wire meshes, 3-D models and 2-D drawings for export to popular computer-aided design (CAD) rendering or other software.
In the ""913 application, some basic real-world examples were discussed. For example, it was suggested that the system could be used to create a three dimensional image of a construction site or a building. This 3-D data could be viewed directly or used to generate CAD drawings.
Because of the high speed and accuracy of the system, further applications have been developed which can greatly benefit from these features. This patent application is intended to describe some of these concepts.
The present invention provides a method for operating a laser scanner. The method includes the step of scanning a site with the laser scanner to create a field survey that has a number of scan points. The method also includes the step of creating a drawing of a structure that has a number of defined points that are positionally related to the scan points in the field survey.
The method further includes the step of rescanning the site with the laser scanner to obtain rescan data. The rescan data corresponds to a number of the scan points. The method additionally includes the step of registering the rescan data with the defined points from the drawing to form registered data. The method also includes the steps of identifying a location of interest from the registered data, and illuminating a location at the site with a laser beam from the laser scanner that corresponds with the location of interest.
In another aspect of the present invention, the method begins with the step of scanning a site with a laser scanner to obtain a number of rescan points that define a first structure. The method further includes the steps of scanning a second structure built to be mated to the first structure to obtain a number of mating points, and comparing the rescan points with the mating points to determine if the second structure can be mated to the first structure.
In a, further aspect of the present invention, the method starts with the step of scanning a site with the laser scanner to obtain a number of scan points that define an opening in a structure. The method additionally includes the steps of scanning an object to be placed within the structure to obtain a number of object points, and comparing the scan points with the object points to determine if the object can be moved through the opening to be placed within the structure.
The present invention also includes a method for grading a tract of land, which has a natural surface, with a programmable earth mover. The method includes the steps of positioning a laser scanner on the tract of land to scan the tract of land, and scanning the tract of land with the laser scanner to define a plurality of first points on the natural surface of the tract of land. The laser scanner having a position in a coordinate system. The first points having positions in the coordinate system and elevation measures of a project.
The method further includes the step of generating a grading plan for the tract of land where the grading plan defines a to-be-constructed surface that differs from the natural surface. The method also includes the step of defining a plurality of second points on the to-be-constructed surface where the second points have positions in the coordinate system and elevation measures of the project. The to-be-constructed surface described by the second points has a corresponding surface described by the first points.
The method additionally includes the step of comparing the elevation measures of specific points on the to-be-constructed surface described by the second points with the elevation measures of points on the corresponding surface described by the first points to define cut points and fill points in the coordinate system. A cut point is defined when the elevation measure of a second point is less than the elevation measure of the corresponding first point. A fill point is defined when the elevation measure of a second point is greater than the elevation measure of the corresponding first point.
The method further includes the step of determining a position of the earth mover in the coordinate system. The method additionally includes the step of operating the earth mover to form the constructed surface by removing earth from the cut points and adding earth to the fill points in response to the information derived from the comparison.
In another aspect of the present invention, the method begins with the step of scanning a site with the laser scanner to obtain a number of scan points. The method also includes the steps of identifying objects within the site by comparing the scan points to predefined geometric objects, and issuing commands based on the identification of the objects.
In a further aspect of the present invention, the method starts with the step of scanning a structure with the laser scanner to obtain a number of scan points. The method additionally includes the step of generating a model of the structure from the scan points. The model, in turn, includes a number of objects. The method further includes the step of adding data links to each object. The data links refer to externally available information about the objects.
In an additional aspect of the present invention, the method begins with the step of scanning an object with the laser scanner to obtain a number of object points. The method also includes the steps of creating a model of the object from the object points where the model includes reproduction information, and controlling a reproducing machine in response to the reproduction information to reproduce the object.
A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description and accompanying drawings that set forth an illustrative embodiment in which the principles of the invention are utilized.